2004 Suzuki Aerio Crank Angle Sensor

It seems I need to replace the crank angle sensor, and I have gotten jerked around a lot by 2 dealerships and an independent repair shop (quotes jumping around, differing information). Really all I want to know is how difficult of a repair is it. I've been told its under the spark plug, behind the transmission, and various other locations.

I can get the part for about $200 online, they want to charge 350 plus labor which goes to around $500-700 is that reasonable?